1. Field of the Invention
The present invention relates to a near field communication antenna device of a mobile terminal. More particularly, the present invention relates to a near field communication antenna device of a mobile terminal that is without an exclusive space in which a near field communication antenna is installed.
2. Description of the Related Art
Recently, as sharing of data, electronic payment systems, and electronic ticketing systems are increasing, more near field communication antenna devices are installed in mobile terminals. This near field communication antenna device has an LC resonance loop antenna utilizing magnetic coupling to perform near field communications of a range of 10 cm to 20 cm using low frequencies of 13.56 MHz (±7 kHz).
The near filed communication antenna should have an overall area greater than 1,500 mm2 and a length of a minor oval axis longer than 30 mm. A plurality of loops formed by an antenna line of the near field communication antenna needs to be formed in order to generate a desired electromotive force. Since a conductive line forming the plurality of loops is formed in a single layer, a near field communication antenna device of a mobile terminal is limited in reducing a width of antenna patterns for forming the plurality of antenna lines. For reference, a width of the antenna patterns described herein is defined as a value in which a sum of widths of portions without conductive lines (which are gaps between antenna lines) is added to a sum of widths of the conductive lines as measured when viewing the near field communication antenna from top. For example, it is assumed that a width of a single antenna line is 0.8 mm and a gap between conductive lines is 0.4 mm. In this case, if a number of turns of a loop formed by the antenna lines is four, an antenna pattern with a width of 4.8 mm is formed, wherein the width is calculated as (0.8 mm+0.4 mm)*4 loops. However, as mobile terminals are made smaller and thinner, it is difficult to secure an adequate area for a near field communication antenna.
Furthermore, in a case where a near field communication antenna is installed or disposed near to or on a battery or a battery cover of a mobile terminal, performance of the near field communication antenna degrades. In addition, in a case where the battery cover is curved, since the near field communication antenna installed on the battery cover does not have a planar shape, performance of the near field communication antenna degrades due to the shape of the antenna.